1. Field of the Invention
This invention relates to carbonaceous materials water mixtures and more particularly to coal water mixtures (CWM) stabilized with condensates of benzene derivatives such as benzene sulfonic acid with an aldehyde such as formaldehyde.
2. Description of the Prior Art
Transport is one of the major problems involved in use of particulate carbonaceous materials such as coal. One method of transport involves carbonaceous materials water mixtures. However, water mixtures of finely ground coal containing over 55 weight percent solids are difficult to pump. When the solids level is increased above 50 weight percent, water and solids tend to separate causing build-up of particles in parts of the pumping system. Dewatering of the slurry causes blockage and jamming in the system.
On the other hand, decreasing the weight percent of water in aqueous coal slurries is desirable because water contributes to the cost of transport and processing operations. When less water is transported, a greater volume of coal can be moved, resulting in transport efficiencies. Water resources are also limited. Also, during burning of coal, significant amounts of heat are required to vaporize the water. As the weight percent of water decreases, the efficiency of the coal burning process increases. Hence, use of higher weight percent solids in carbonaceous water mixtures than were heretofore feasible are of great importance.
U.S. Pat. No. 4,282,006--Funk, Aug. 4, 1981, describes a pipeline pumpable coal water slurry having a high content of coal particles with a minimum of void spaces and a maximum of particle surface area to enhance dispersing effects generated by electrolytes and/or dispersing agents added to the slurry. For dispersing agents, see column 29, line 53 to colum 31, line 9, including condensed mononaphthalene sulfonic acid and its sodium and ammonium salts (column 30, lines 19 and 20).
U.S. Pat. No. 4,330,301--Yamamura et al, May 18, 1982, describes dispersants for aqueous coal slurries including sodium and ammonium salts of condensation products of naphthalene sulfonic acid and formaldehyde condensates. See column 2, lines 41 to 43 and columns 5 and 6.